Vitamin E concentrations were determined in plasma and platelet samples from 23 diabetic and 30 control human subjects. The mean concentrations of α and total tocopherols in the plasma and platelets of the diabetics were higher than that of the controls. The mean γ tocopherol concentrations in both plasma and platelets were similar in diabetics and controls. The platelet vitamin E concentrations decreased significantly with age in only the controls and not in the diabetics. Thus diabetics have higher concentrations of tocopherols in blood platelets and plasma. The total plasma tocopherol concentrations correlated significantly with total plasma cholesterol, triglyceride, and total lipid concentrations in both diabetic and control groups. However, no significant correlations were observed between platelet tocopherol levels and plasma lipids in either group. In five subjects plasma and platelet vitamin E concentrations remained unchanged during standard glucose tolerance tests.